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-rw-r--r--libamu/alloca.c504
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diff --git a/libamu/alloca.c b/libamu/alloca.c
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-/* alloca.c -- allocate automatically reclaimed memory
- (Mostly) portable public-domain implementation -- D A Gwyn
-
- This implementation of the PWB library alloca function,
- which is used to allocate space off the run-time stack so
- that it is automatically reclaimed upon procedure exit,
- was inspired by discussions with J. Q. Johnson of Cornell.
- J.Otto Tennant <jot@cray.com> contributed the Cray support.
-
- There are some preprocessor constants that can
- be defined when compiling for your specific system, for
- improved efficiency; however, the defaults should be okay.
-
- The general concept of this implementation is to keep
- track of all alloca-allocated blocks, and reclaim any
- that are found to be deeper in the stack than the current
- invocation. This heuristic does not reclaim storage as
- soon as it becomes invalid, but it will do so eventually.
-
- As a special case, alloca(0) reclaims storage without
- allocating any. It is a good idea to use alloca(0) in
- your main control loop, etc. to force garbage collection. */
-
-#ifdef HAVE_CONFIG_H
-#include <config.h>
-#endif
-
-#ifdef HAVE_STRING_H
-#include <string.h>
-#endif
-#ifdef HAVE_STDLIB_H
-#include <stdlib.h>
-#endif
-
-#ifdef emacs
-#include "blockinput.h"
-#endif
-
-/* If compiling with GCC 2, this file's not needed. */
-#if !defined (__GNUC__) || __GNUC__ < 2
-
-/* If someone has defined alloca as a macro,
- there must be some other way alloca is supposed to work. */
-#ifndef alloca
-
-#ifdef emacs
-#ifdef static
-/* actually, only want this if static is defined as ""
- -- this is for usg, in which emacs must undefine static
- in order to make unexec workable
- */
-#ifndef STACK_DIRECTION
-you
-lose
--- must know STACK_DIRECTION at compile-time
-#endif /* STACK_DIRECTION undefined */
-#endif /* static */
-#endif /* emacs */
-
-/* If your stack is a linked list of frames, you have to
- provide an "address metric" ADDRESS_FUNCTION macro. */
-
-#if defined (CRAY) && defined (CRAY_STACKSEG_END)
-long i00afunc ();
-#define ADDRESS_FUNCTION(arg) (char *) i00afunc (&(arg))
-#else
-#define ADDRESS_FUNCTION(arg) &(arg)
-#endif
-
-#if __STDC__
-typedef void *pointer;
-#else
-typedef char *pointer;
-#endif
-
-#ifndef NULL
-#define NULL 0
-#endif
-
-/* Different portions of Emacs need to call different versions of
- malloc. The Emacs executable needs alloca to call xmalloc, because
- ordinary malloc isn't protected from input signals. On the other
- hand, the utilities in lib-src need alloca to call malloc; some of
- them are very simple, and don't have an xmalloc routine.
-
- Non-Emacs programs expect this to call use xmalloc.
-
- Callers below should use malloc. */
-
-#ifndef emacs
-#define malloc xmalloc
-#endif
-extern pointer malloc ();
-
-/* Define STACK_DIRECTION if you know the direction of stack
- growth for your system; otherwise it will be automatically
- deduced at run-time.
-
- STACK_DIRECTION > 0 => grows toward higher addresses
- STACK_DIRECTION < 0 => grows toward lower addresses
- STACK_DIRECTION = 0 => direction of growth unknown */
-
-#ifndef STACK_DIRECTION
-#define STACK_DIRECTION 0 /* Direction unknown. */
-#endif
-
-#if STACK_DIRECTION != 0
-
-#define STACK_DIR STACK_DIRECTION /* Known at compile-time. */
-
-#else /* STACK_DIRECTION == 0; need run-time code. */
-
-static int stack_dir; /* 1 or -1 once known. */
-#define STACK_DIR stack_dir
-
-static void
-find_stack_direction ()
-{
- static char *addr = NULL; /* Address of first `dummy', once known. */
- auto char dummy; /* To get stack address. */
-
- if (addr == NULL)
- { /* Initial entry. */
- addr = ADDRESS_FUNCTION (dummy);
-
- find_stack_direction (); /* Recurse once. */
- }
- else
- {
- /* Second entry. */
- if (ADDRESS_FUNCTION (dummy) > addr)
- stack_dir = 1; /* Stack grew upward. */
- else
- stack_dir = -1; /* Stack grew downward. */
- }
-}
-
-#endif /* STACK_DIRECTION == 0 */
-
-/* An "alloca header" is used to:
- (a) chain together all alloca'ed blocks;
- (b) keep track of stack depth.
-
- It is very important that sizeof(header) agree with malloc
- alignment chunk size. The following default should work okay. */
-
-#ifndef ALIGN_SIZE
-#define ALIGN_SIZE sizeof(double)
-#endif
-
-typedef union hdr
-{
- char align[ALIGN_SIZE]; /* To force sizeof(header). */
- struct
- {
- union hdr *next; /* For chaining headers. */
- char *deep; /* For stack depth measure. */
- } h;
-} header;
-
-static header *last_alloca_header = NULL; /* -> last alloca header. */
-
-/* Return a pointer to at least SIZE bytes of storage,
- which will be automatically reclaimed upon exit from
- the procedure that called alloca. Originally, this space
- was supposed to be taken from the current stack frame of the
- caller, but that method cannot be made to work for some
- implementations of C, for example under Gould's UTX/32. */
-
-pointer
-alloca (size)
- unsigned size;
-{
- auto char probe; /* Probes stack depth: */
- register char *depth = ADDRESS_FUNCTION (probe);
-
-#if STACK_DIRECTION == 0
- if (STACK_DIR == 0) /* Unknown growth direction. */
- find_stack_direction ();
-#endif
-
- /* Reclaim garbage, defined as all alloca'd storage that
- was allocated from deeper in the stack than currently. */
-
- {
- register header *hp; /* Traverses linked list. */
-
-#ifdef emacs
- BLOCK_INPUT;
-#endif
-
- for (hp = last_alloca_header; hp != NULL;)
- if ((STACK_DIR > 0 && hp->h.deep > depth)
- || (STACK_DIR < 0 && hp->h.deep < depth))
- {
- register header *np = hp->h.next;
-
- free ((pointer) hp); /* Collect garbage. */
-
- hp = np; /* -> next header. */
- }
- else
- break; /* Rest are not deeper. */
-
- last_alloca_header = hp; /* -> last valid storage. */
-
-#ifdef emacs
- UNBLOCK_INPUT;
-#endif
- }
-
- if (size == 0)
- return NULL; /* No allocation required. */
-
- /* Allocate combined header + user data storage. */
-
- {
- register pointer new = malloc (sizeof (header) + size);
- /* Address of header. */
-
- if (new == 0)
- abort();
-
- ((header *) new)->h.next = last_alloca_header;
- ((header *) new)->h.deep = depth;
-
- last_alloca_header = (header *) new;
-
- /* User storage begins just after header. */
-
- return (pointer) ((char *) new + sizeof (header));
- }
-}
-
-#if defined (CRAY) && defined (CRAY_STACKSEG_END)
-
-#ifdef DEBUG_I00AFUNC
-#include <stdio.h>
-#endif
-
-#ifndef CRAY_STACK
-#define CRAY_STACK
-#ifndef CRAY2
-/* Stack structures for CRAY-1, CRAY X-MP, and CRAY Y-MP */
-struct stack_control_header
- {
- long shgrow:32; /* Number of times stack has grown. */
- long shaseg:32; /* Size of increments to stack. */
- long shhwm:32; /* High water mark of stack. */
- long shsize:32; /* Current size of stack (all segments). */
- };
-
-/* The stack segment linkage control information occurs at
- the high-address end of a stack segment. (The stack
- grows from low addresses to high addresses.) The initial
- part of the stack segment linkage control information is
- 0200 (octal) words. This provides for register storage
- for the routine which overflows the stack. */
-
-struct stack_segment_linkage
- {
- long ss[0200]; /* 0200 overflow words. */
- long sssize:32; /* Number of words in this segment. */
- long ssbase:32; /* Offset to stack base. */
- long:32;
- long sspseg:32; /* Offset to linkage control of previous
- segment of stack. */
- long:32;
- long sstcpt:32; /* Pointer to task common address block. */
- long sscsnm; /* Private control structure number for
- microtasking. */
- long ssusr1; /* Reserved for user. */
- long ssusr2; /* Reserved for user. */
- long sstpid; /* Process ID for pid based multi-tasking. */
- long ssgvup; /* Pointer to multitasking thread giveup. */
- long sscray[7]; /* Reserved for Cray Research. */
- long ssa0;
- long ssa1;
- long ssa2;
- long ssa3;
- long ssa4;
- long ssa5;
- long ssa6;
- long ssa7;
- long sss0;
- long sss1;
- long sss2;
- long sss3;
- long sss4;
- long sss5;
- long sss6;
- long sss7;
- };
-
-#else /* CRAY2 */
-/* The following structure defines the vector of words
- returned by the STKSTAT library routine. */
-struct stk_stat
- {
- long now; /* Current total stack size. */
- long maxc; /* Amount of contiguous space which would
- be required to satisfy the maximum
- stack demand to date. */
- long high_water; /* Stack high-water mark. */
- long overflows; /* Number of stack overflow ($STKOFEN) calls. */
- long hits; /* Number of internal buffer hits. */
- long extends; /* Number of block extensions. */
- long stko_mallocs; /* Block allocations by $STKOFEN. */
- long underflows; /* Number of stack underflow calls ($STKRETN). */
- long stko_free; /* Number of deallocations by $STKRETN. */
- long stkm_free; /* Number of deallocations by $STKMRET. */
- long segments; /* Current number of stack segments. */
- long maxs; /* Maximum number of stack segments so far. */
- long pad_size; /* Stack pad size. */
- long current_address; /* Current stack segment address. */
- long current_size; /* Current stack segment size. This
- number is actually corrupted by STKSTAT to
- include the fifteen word trailer area. */
- long initial_address; /* Address of initial segment. */
- long initial_size; /* Size of initial segment. */
- };
-
-/* The following structure describes the data structure which trails
- any stack segment. I think that the description in 'asdef' is
- out of date. I only describe the parts that I am sure about. */
-
-struct stk_trailer
- {
- long this_address; /* Address of this block. */
- long this_size; /* Size of this block (does not include
- this trailer). */
- long unknown2;
- long unknown3;
- long link; /* Address of trailer block of previous
- segment. */
- long unknown5;
- long unknown6;
- long unknown7;
- long unknown8;
- long unknown9;
- long unknown10;
- long unknown11;
- long unknown12;
- long unknown13;
- long unknown14;
- };
-
-#endif /* CRAY2 */
-#endif /* not CRAY_STACK */
-
-#ifdef CRAY2
-/* Determine a "stack measure" for an arbitrary ADDRESS.
- I doubt that "lint" will like this much. */
-
-static long
-i00afunc (long *address)
-{
- struct stk_stat status;
- struct stk_trailer *trailer;
- long *block, size;
- long result = 0;
-
- /* We want to iterate through all of the segments. The first
- step is to get the stack status structure. We could do this
- more quickly and more directly, perhaps, by referencing the
- $LM00 common block, but I know that this works. */
-
- STKSTAT (&status);
-
- /* Set up the iteration. */
-
- trailer = (struct stk_trailer *) (status.current_address
- + status.current_size
- - 15);
-
- /* There must be at least one stack segment. Therefore it is
- a fatal error if "trailer" is null. */
-
- if (trailer == 0)
- abort ();
-
- /* Discard segments that do not contain our argument address. */
-
- while (trailer != 0)
- {
- block = (long *) trailer->this_address;
- size = trailer->this_size;
- if (block == 0 || size == 0)
- abort ();
- trailer = (struct stk_trailer *) trailer->link;
- if ((block <= address) && (address < (block + size)))
- break;
- }
-
- /* Set the result to the offset in this segment and add the sizes
- of all predecessor segments. */
-
- result = address - block;
-
- if (trailer == 0)
- {
- return result;
- }
-
- do
- {
- if (trailer->this_size <= 0)
- abort ();
- result += trailer->this_size;
- trailer = (struct stk_trailer *) trailer->link;
- }
- while (trailer != 0);
-
- /* We are done. Note that if you present a bogus address (one
- not in any segment), you will get a different number back, formed
- from subtracting the address of the first block. This is probably
- not what you want. */
-
- return (result);
-}
-
-#else /* not CRAY2 */
-/* Stack address function for a CRAY-1, CRAY X-MP, or CRAY Y-MP.
- Determine the number of the cell within the stack,
- given the address of the cell. The purpose of this
- routine is to linearize, in some sense, stack addresses
- for alloca. */
-
-static long
-i00afunc (long address)
-{
- long stkl = 0;
-
- long size, pseg, this_segment, stack;
- long result = 0;
-
- struct stack_segment_linkage *ssptr;
-
- /* Register B67 contains the address of the end of the
- current stack segment. If you (as a subprogram) store
- your registers on the stack and find that you are past
- the contents of B67, you have overflowed the segment.
-
- B67 also points to the stack segment linkage control
- area, which is what we are really interested in. */
-
- stkl = CRAY_STACKSEG_END ();
- ssptr = (struct stack_segment_linkage *) stkl;
-
- /* If one subtracts 'size' from the end of the segment,
- one has the address of the first word of the segment.
-
- If this is not the first segment, 'pseg' will be
- nonzero. */
-
- pseg = ssptr->sspseg;
- size = ssptr->sssize;
-
- this_segment = stkl - size;
-
- /* It is possible that calling this routine itself caused
- a stack overflow. Discard stack segments which do not
- contain the target address. */
-
- while (!(this_segment <= address && address <= stkl))
- {
-#ifdef DEBUG_I00AFUNC
- fprintf (stderr, "%011o %011o %011o\n", this_segment, address, stkl);
-#endif
- if (pseg == 0)
- break;
- stkl = stkl - pseg;
- ssptr = (struct stack_segment_linkage *) stkl;
- size = ssptr->sssize;
- pseg = ssptr->sspseg;
- this_segment = stkl - size;
- }
-
- result = address - this_segment;
-
- /* If you subtract pseg from the current end of the stack,
- you get the address of the previous stack segment's end.
- This seems a little convoluted to me, but I'll bet you save
- a cycle somewhere. */
-
- while (pseg != 0)
- {
-#ifdef DEBUG_I00AFUNC
- fprintf (stderr, "%011o %011o\n", pseg, size);
-#endif
- stkl = stkl - pseg;
- ssptr = (struct stack_segment_linkage *) stkl;
- size = ssptr->sssize;
- pseg = ssptr->sspseg;
- result += size;
- }
- return (result);
-}
-
-#endif /* not CRAY2 */
-#endif /* CRAY */
-
-#endif /* no alloca */
-#endif /* not GCC version 2 */